This invention relates to improvements in window construction and more particularly to an improved mullion for high performance windows.
The strength of the mullion which provides the central support between window lights in a divided window structure is an important factor in giving wind load resistance and hence rating of the window. The importance of this mullion is increased with increasing window height with windows, for example, having a height of 72 inches being frequently encountered.
The mullions in such windows have been formed as hollow generally T-shaped extrusions with an enlarged hollow head, a narrow stem depending from the head to a hollow foot, To provide strength to the mullion it has been considered necessary to provide the mullion extrusion with a series of internal walls. To further increase the strength of the mullion, a metal insert has been introduced into the hollow mullion head. However, the presence of the internal walls of the mullion extrusion blocks the use of any insert spanning between the head and foot of the mullion.
It is the object of the present invention to provide a mullion having greatly increased strength over existing mullions.
According to the present invention, the mullion for a divided window comprises a generally T-shaped hollow plastic extrusion in which there are no internal walls between the hollow head and the hollow foot of the T and providing a generally T-shaped reinforcing insert adapted to be sleeved down into the plastic T with the insert having a head portion bracing the extruded plastic head, a stem portion extending from the head down through the plastic stem and into the foot of the plastic extrusion.
According to the preferred form of the invention, interengaging means are provided between the insert and the plastic extrusion to prevent spreading of the stem portion of the plastic extrusion.
In this connection, according to a preferred form of the invention, the plastic extrusion has longitudinal internal ribs at each side of the stem portion where it opens into the hollow head of the extrusion and where it opens into the hollow foot of the extrusion and the reinforcing insert has lateral arms with end flanges or fingers to engage over the internal plastic ribs to prevent their separation under loading. Further, according to the preferred form of the invention, the reinforcing insert is formed with laterally extending arms intermediate the head of the T and the rib engaging arms where the stem of the plastic T opens into the head of the plastic T. These intermediate arms being provided at their ends with part circular screw receptors.
Similarly, according to a preferred form of the invention, the foot portion of the reinforcing insert is provided with a central part cylindrical portion forming a screw receptor.
Again, according to the preferred form of the invention, the metal insert is an elongated aluminum extrusion. However, other suitable inserts such as those formed from fiberglass by pultrusion may also be used.